Okay I know the wires you're talking about. I'll try to short them in the morning and see what happens. If that works I can use my mulimeter to check for continuity.J,
Excellent!!! The heater is normally controlled by a small relay on one of the boards... It basically interrupts the path for 24 volts AC from the heater and then back to the heater. The Circuit is called the Firemans switch.. When the relay is open the heater does not work, and when the relay is closed the heater turn on. The heater is normally set to full hot and the automation monitors the water temp probe. If the water is less than the set point that you enter into the automation, the relay closes and turn the heater on. When the water temp gets up to the set point, the relay opens and the heater stops.. You should be able to just remove the two wires going to the heater connection and short them together and see if the heater fires up.. If you have a meter, you can then test the relay to see if you have continuity or not.
The heater connection is the two pin connector with the black and white wires at the top left of your picture..
Glad you got it working, almost...
Thanks again, Jeff